chore(ci): define a test script so the workflow runs the suite

.github/workflows/test.yml only runs `bun run test` when package.json
defines a "test" script, and otherwise prints "No test script defined —
skipping". No such script existed, so every green run to date was green
because nothing ran: the 25 tests under tests/ were never executed in CI.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: ralyodio

package.json

@@ -7,7 +7,8 @@
     "dev": "next dev -p 8080",
     "build": "next build",
     "start": "next start -p ${PORT:-8080}",
-    "lint": "next lint"
+    "lint": "next lint",
+    "test": "bun test tests/"
   },
   "dependencies": {
     "@libsql/client": "^0.15.7",